What are the sensitivity and specificity of serial measurements of peak flow in the diagnosis of occupational asthma?

The following references have been associated with this question by users of this website. They do not form part of the BOHRF occupational asthma guidelines.

ALFRED Viegi 1986
burgeps Girard 2004
burgeps Girard 2004 Study of workers investigated by specific challenge in Canada, 45/94 excluded. Unable to perform specific challenge 9/94, unable to induce sputum 7/94, uninterpretable pef 3/49, no induced sputum 1/49. Symptom scores showed large changes between work and rest, similar in challenge positive and negative subjects, raising possibilities of low sensitivity of specific challenge. Similar improvement 9about one doubling) in PC20 in challenge positive and negative workers. Eosinophils in induced sputum showed reduced changes in those on ICS. Increase in sputum eosinophils >1% sensitivity 65.2% specificity 76%; Increase in sputum eosinophils >2% sensitivity 52% specificity 80%; Increase in sputum eosinophils >6.4% sensitivity 26.1% specificity 92%; PEF analysis likely to be of reduced quality records as only 2 complexes; sensitivity 34.8 by Oasys, specificity 65.2%. addins sputon eosinophils increasing by >1 or 2% increased sensitivity to 50% and 36.4% (specificities 75 and 80%). Expert agreement of PEF records poor (Cohens Kappa 0.4-0.6). This is a difficult paper to turn into evidence. All modalities performed poorly compared with specific challenge, specific challenge performed poorly compared with symptom diaries. Sputum eosinophilia normal in at least some with positive challenges (fig 1) probably about 50% of those with positive challenges. Results inadequate to support use of induced sputum as part of diagnostic work-up
burgeps Munoz 2004 4/5 positive by unspecified criteria
burgeps Moore 2009 The Area Between Curves (ABC) score from at leat 8 workdays and 3 restdays has a 68% sensitivity 91% specificity for 2-hourly readings against independant standards of diagnosis, mostly specific challenge testing but also 4 fold changes in NSBR or positive IgE to a well characterised antigen together with a strong history and evidence of asthma.
burgeps Moore 2009 In enzyme detergent workers 79% (n = 27) of those with a final diagnosis of occupational asthma had peak flow records confirming the diagnosis using the Oasys rest-work score >= 16l/min after day interpretation; for an Oasys-2 score of >2.5 sensitivity was 76%. The final diagnosis was based on a history of work-related asthma symptoms and positive IgE to detergent enzymes. The peak flow records were not used for the diagnosis of occupational asthma in this study (but was in the original report of this outbreak). Specificity could not be assessed as PEF records were not attempted in asymptomatic workers. (Using a clinical diagnosis including viewing the PEF records without Oasys plotting and incorporating some specific challenges the sensitivity of the Oasys-2 score >2.5 was 77%
burgeps Park 2009 This paper shows that In workers with challenge positive occupational asthma the mean change across shift of pef is very small in workers on a day or morning shift. (about 5 litres/min) because the PEF usually increases after waking due to spontaneous diurnal variation. Using a cut off of 5 litres/min gives a sensitivity of 50% and a specificity of 91%. Using Oasys analysis of the same record an Oasys score >2.5 had a sensitivity of 83% and a specificity of 91%. The Area Between th Curves (ABC) score had a sensitivity of 67% and a specificity of 100%. There is clear benefit from 2-hourly PEF records over pre and post shift changes.
Vicky Moore Hayati 2006
Vicky Moore Hayati 2008
Cedd Burge Burge 2009 A minimum of four time point comparisons were needed (43% of available records - but improvable if collecting data prospectively). Sensitivity of 67% and a specificity of 99%.
burgeps Moore 2010 ABC score improved by having at least a week off work
burgeps Anees 2011 When the mean PEF on workdays (starting with the first reading at work and continuing till the last reading before work on the next day, i.e. "day interpreted")is compared with the mean PEF on days away from exposure, a difference of 16 litres/min is outside the 95% CI for readings taken in non-asthmatics exposed to high levels of a respiratory irritant (grain). Taking a mean rest-work PEF >16 litres/min achieved a sensitivity of 68% and specificity 95% in indeendently diagnosed occupational asthmatics and asthmatic controls. An increase in diurnal variation on workdays of >7% (the upper 95% CI for aasthmatic controils) had a sensitivity of only 27% for the diagnosis of OA. The difference between maximum PEF on workdays and minimum PEF on rest days (as reported in Cote J, Kennedy S, ChanYeung M , Quantitative Versus Qualitative Analysis Of Peak Expiratory Flow In Occupational Asthma, Thorax, 1993; 48:48-51) had a sensitivity of <10% against non-occupational asthmatic controls
burgeps Moore 2012
burgeps Burge 2015

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